Metal superconductors, compound superconductors and oxide superconductors have been known and various applications thereof have been studied. A superconductor has its electrical resistance made zero when it is maintained at a temperature not higher than a critical temperature. Generation of high magnetic field, high density transfer of large current and so on have been tried utilizing this characteristic.
Recently, attention is beginning to center on oxide superconductive materials, which have higher critical temperature at which the superconductive phenomenon occurs. Such superconductive materials can be used for power transmission and distribution, electrical connection between various equipment and elements, AC coils and so on, when they are turned into longitudinal wire bodies.
Various methods have been known to fabricate wires of oxide superconductive materials. In one method, powder of oxide superconductive material is filled in a metal pipe and the cross section thereof is reduced. In another, a layer of oxide superconductive material is formed on a longitudinal base. Gas phase thin film deposition such as vapor deposition, sputtering and CVD may be applied as a method of forming the oxide superconductive layer.
Generally, oxide superconductive materials are weak on strain, especially tensile strain, and when a tensile strain is generated, for example, superconductivity such as critical temperature and current density is significantly degraded. When a longitudinal oxide superconductive wire is bent, a tensile strain is generated in some portion or other inevitably. In order to lengthen the oxide superconductor while suppressing generation of strain such as the tensile strain as much as possible, a method of forming a thin oxide superconductive layer on a fiber-type or film-type thin or narrow flexible base has been known. By this method, the wire can be bent to be have smaller diameter with the same allowable strain.
However, there is a limit in the above described method, and oxide superconductive wires which are stronger against strain have been desired for practical use.
Therefore, an object of the present invention is to provide oxide superconductive wires which are stronger against strains.
Another object of the present invention is to provide a method of manufacturing the above described oxide superconductive wires which are stronger against strains.
A further object of the present invention is to provide products using the above described oxide superconductive wires.